1. Field of the Invention
The present invention relates to an escalator, and more particularly to an improved escalator terminal rail system capable of minimizing noise and vibration caused by an impact resulting from a step rear roller passing through a channel formed in the terminal rail system.
2. Description of the Prior Art
As shown in FIGS. 1 and 2, a conventional escalator includes: a pair of hand rails 1 for concurrently moving along a predetermined track thereof; a step unit 2 for transporting passengers; and a mechanical assembly 3 for driving the hand rails 1 and the step unit 2.
The mechanical assembly 3 includes: a driving unit provided with a motor 4, a speed reducer 5, a driving chain 6, a driving sprocket 7, a first terminal gear 8, a second terminal gear 11, a driving shaft 12 and a terminal rail 13; and a moving unit provided with a plurality of steps 9, a step chain 10, a step rear roller 14, and a step front roller 15.
With reference to FIGS. 3 and 4, the terminal rail 13 is provided with a semicircular inner casing 18 and a semicircular outer casing 19, wherein an end portion of the inner casing 18 is engaged to an upper end portion of a lower guide rail 17.
The thusly constituted conventional terminal rail system serves to guide the step rear roller 15 and is not furnished with an extra device for removing or decreasing noise or vibration, and a generally adopted method therefor is to relieve an escalation impact by simply applying a precise fabrication to the terminal rail 13 so as to maintain a minimum gap between the inner casing 18 and the outer casing 19, through which gap does the step rear roller 15 passes.
The operation of the thusly constituted escalator will now be described.
First, power generated by the motor 4 in the mechanical assembly 3 is transferred to the speed reducer 5. In accordance with driving of the sprocket 7 connected to the speed reducer 5, the driving chain 6 is rendered driven. The first terminal gear 8 sharing a shaft with the driving sprocket 7 operates the step chain 10 being engaged to the steps 9 which circulate between the first terminal gear 8 and the second terminal gear 11.
The step front roller 14 travels along the upper guide rail 16, and the step rear roller 15 travels along the lower guide rail 17, so that when the step 9 reaches to an upper or lower end portion of the escalator, the step rear roller 15 is turned around through a channel formed in the terminal rail 13.
As shown in FIG. 4, at the upper and lower end portion of the escalator, the step front roller 14 is turned around and engaged to the terminal gear 8, and the step rear roller 15 is turned around along the terminal rail 13. At this time, the step rear roller 15 travels being attached to an outer surface of the inner casing 18, and when the step rear roller 15 comes up to a curved portion leading to the terminal rail 13, the step rear roller 15 begins turning around and closely attached to an inner surface of the outer casing 19.
However, the above-described conventional terminal rail 13 has a disadvantage, in that during operation of the escalator, the step rear roller 15 at the upper or lower end portion of the escalator hits onto the inner surface of the outer casing 19 therein, thereby resulting in serious noise and vibration.
The noise and vibration being caused by such impact has been one of the most desperate problems that the conventional escalator has yet to solve, and despite continuous efforts so far made to overcome such a disadvantage, the noise and vibration still remain annoying.
In recent years, in an effort to unveil the cause of such noise and vibration, there has been carried out a noise measurement experiment employing a Taguchi experimental method which considers all the possible noise factors.
FIG. 5 illustrates the effects of respective noise generating factors under the Taguchi method, wherein the steeper the slope of any of the factors in the graph, the more effective it is to restrain from noise occurrence.
The experiment has revealed that the cause of noise and vibration occurring when the step 9 turns around at the upper and lower end portion of the escalator, is directed to the terminal rail 13. Meanwhile, it is also proved that "C" factors as shown in FIG. 5 have relation to increase or decrease of the impact-caused noise and vibration simply resulting from an impact caused by the step rear roller 15.
Here, minium (red lead) is employed in order to discover noise mechanism and location being impacted thereon with regard to the terminal rail 13, and as shown in FIG. 6, the step rear roller 15 travels along the outer surface of the semicircular inner casing 18 of the terminal rail 13 and is deviated off from a curve start point B of the outer surface of the inner casing 18. Then, the step rear roller 15 is impacted on a portion A (spaced about 45 degrees upwardly from an imaginary line extended from a horizontal surface line of the inner casing 18) of the inner surface of the outer casing 19 of the terminal rail 13, and turned around on and along the inner surface of the outer casing 19 of the terminal rail 13.
The step rear roller 15 does not initially touch a portion of the inner surface of the outer casing 19 corresponding to an imaginary line extended from the portion B but touches a slightly more upward portion of the inner surface of the outer casing 19 than the imaginary line extended from the portion B. This is because the step front roller 14 is driven forwardly in conjunction with the terminal gear 8 and a driving force occurring when the step 9 is being lifted is applied thereto. Also, in accordance with the experimental result with regard to the cycle of the step rear roller 15 being moved in accordance with the guide of the terminal rail 13, it is known that pressure and impact have significantly influenced the outer casing 19 of the terminal rail 13.
Because the cycle of the step rear roller 15 remains constant, the step rear roller 15 renders repeated impacts on the portion A of the terminal rail 13, thereby generating serious noise and vibration.
Also, the step rear roller 15 travelling along the conventional terminal rail 13 springs up from the curve start point B to the portion A of the outer casing 19 while proceeded along the semicircular inner casing 18 of the terminal rail 13.
In short, the conventional terminal rail system for an escalator has several disadvantages, wherein: the step rear roller 15 generates a significant amount of noise each time the step rear roller 15 is impacted on the portion A; each moment the step rear roller 15 is impacted on the portion A at an average rate of 0.8 sec/step, the thusly amplified pulsation increases vibration of the steps 9; the step rear roller 15 and the terminal rail 13 are directly impacted on each other, thereby resulting in decreased longevity of each thereof; the rougher the inner surface of the outer casing 19, the larger becomes the noise; and in order to decrease the noise and vibration being caused by the impact of the step rear roller 15 on the portion A, the gap between the semicircular inner casing 18 and the outer casing 19 may be obtained by a precise fabrication thereof, thereby resulting in increased cost and decreased productivity in fabrication and assembly thereof.